start moving malloc and friends in

userland/glibc/brk.c

@@ -0,0 +1,24 @@
+/* https://cirosantilli.com/linux-kernel-module-cheat#brk */
+
+#define _GNU_SOURCE
+#include <assert.h>
+#include <unistd.h>
+
+int main(void) {
+    void *b = sbrk(0);
+    int *p = (int *)b;
+
+    /* Move it 2 ints forward */
+    brk(p + 2);
+
+    /* Use the ints. */
+    *p = 1;
+    *(p + 1) = 2;
+    assert(*p == 1);
+    assert(*(p + 1) == 2);
+
+    /* Deallocate back. */
+    brk(b);
+
+    return 0;
+}